Estimation and Measurement of Bed Material Shear Stresses in Erosion Rate Testing Devices

Abstract

The sediment erosion rate flume (SERF) is used to evaluate various methods to estimate shear stresses in a flume-style erosion rate testing device. Results show that direct shear stress measurements most closely correspond to shear stress estimates obtained from the Colebrook equation using a roughness height of approximately 77% of the sediment particle diameter. Using pressure drops to estimate shear stress appears to underestimate rough sample (grain sizes >0.25 mm) stresses. Likewise, smooth-wall assumptions and analytical methods also appear to produce lower than expected results for similar heights. Colebrook equation results should be interpreted as “instrument specific” because of the different devices’ hydraulic diameters.